I just updated this through the plugins section and get this error every time before it loads:

Warning: array_merge() [function.array-merge]: Argument #1 is not an array in /home/multifac/www/schooldays/School/wp-content/plugins/cleverness-to-do-list/includes/cleverness-to-do-list-loader.class.php on line 22

When you try to set any of the options, you get the above as well as the below.

Warning: Cannot modify header information – headers already sent by (output started at /home/multifac/www/schooldays/School/wp-content/plugins/cleverness-to-do-list/includes/cleverness-to-do-list-loader.class.php:22) in /home/multifac/www/schooldays/School/wp-includes/pluggable.php on line 866

Updating through the WP interface just didn’t work. I had to delete it altogether and reinstall with 3.0 as a fresh install. Then it was fine. I had 2.2.8 and I think it was the file name changes that just wouldn’t allow it to be updated!